Hydrometer



@et E5, 19%. F. v. H|ERGESELL HYDROMETER Filed Feb. '7, 1935 INVENTOR FRIDBY HIERGEELL- ATTORNEYS @Neri mi L Patented Oct. 15, 1935 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to hydrometers and similar measuring instruments, and refers particularly to such an instrument of the type wherein the ballast thereof is sealed into the bulb por- 5 tion so as to form a rigid unit with the latter, and

in case of breakage of said bulb portion during' use, to retain its form as a solid impervious mass which is substantially chemically neutral to those fluids which it is desired to gage by means of the instrument.

The main object of my invention is to provide an improved hydrometer as indicated, wherein the ballast, despite the fact that it is principally composed of the usual small shot for accuracy in Calibrating the instrument, nevertheless is consolidated into a coherent mass and provided with a chemically inert, impervious exterior coating or sheath which serves the twofold purpose of vprotecting the shot in the mass from making contact with and contaminating fluids under test if `the glass of the bulb portion is broken, and also of forming an adherent interior reinforcement for the bulb which tends to prevent breakage thereof from shocks and blows, and upon actual fracture of the glass, to retain the glass fragments in place.

Another obj ect is to have a rigid ballast within an instrument of this class, which has an improved and attractive appearance by virtue of any desired coloration uniformly applied to the protective coating of the ballast so as to conceal the latter.

A further object is to produce an instrument of this character which, by virtue of the nature of the coherent ballast and the protective coating or sheath therefor, may be given an eflicient and strong physical form which Acooperates to the utmost with said ballast and coating to form an exceedingly strong and physically resistant whole 40" blows or in any case easily damaged or apt to which is not sensitive to accidental shocks and and gradually communicates such changes to the ballast within.

It is also an object to provide a novel hydrometer which may be given a pleasing form and attractive appearance which will enhance its 5 y marketable properties without materially increasing its cost of production.

Referring now to the accompanying drawing forming part hereof,

Figure 1 illustrates a hydrometer which is made l0 according to the invention and embodies the novel features thereof in a practical form.

Figure 2 is a transverse section of Figure 1 on line 2 2 on a large scale,

Figure 3 is a fragmentary vertical section of 15 Figure 1 on line 3-3 on a greatly enlarged scale.

Throughout the views, the same reference numerals indicate the same or like parts.

It is a common experienceof those who have occasion to frequently use hydrometers of the 20 common type, that such instruments are all too fragile, yso that a slight accidental shock or sudden contact with another object or exposure to great temperature changes may often cause breakage of the bulbi and immediate `release of the ballast into the fluid which may be undergoing investigation. For chemists, such an eventuality is particularly offensive, and possibly dangerous, as the ballast, usually consisting of lead or other metallic shot, will certainly react with and contaminate most of the fluid media and bodies with which a chemist must deal. Not only the hydrometer is then lost, but perhaps a valuable liquid or solution has been ruined, or an important experiment interrupted or even lost. Other disadvantages might also be enumerated, such as that the loose shot ordinarily used as ballast may conceivably shift in position and dislocate the center of gravity of the instrument as a whole, and thus render the same inaccurate by tilting the latter in use.

The present invention has consequently been designed with the foregoing objects in view, and very definitely to eliminate the disadvantages above mentioned in connection with hydrometers as made heretofore.

Hence, referring again to the drawing, I practice rny invention by providing a hydrometer, generally indicated by l, with the usual stem 4 which either contains a strip of paper having a 50 series of graduations, as at 5, or is etched with such indicia, as desired. To this stem 4 is fused an elongated bulb 6 which is formed at the bottom so as to terminate in a reinforced conical end l.

It is, of course intended that the stem 4 and bulb 55 6 shall be of glass but other suitable materials may also be used. However, before the upper portion of the bulb is fused to the stem, or if already attached thereto while the upper end of the stem is retained open, a condensation product of phenol, for example, that compound known as bakelite is carefully poured into the lower end of bulb 6 so that the upper level of the phenol condensation product rises gradually to a distance above the lower conical portion into the cylindrical portion of the bulb. When the proper level has been reached, in any case considerably above the level of the ballast which is subsequently to be inserted, no further amount of phenol rcondensation product is poured in, but insteadya tube is temporarily inserted and the greater part of the phenol condensationproduct withdrawn by Y suction until merely the film thereof that adheres to the glass remains. This lm has then an even upper edge which represents thehighest level which was attained by the iluid phenol condensation product. f

The interior nlm or coating of the mentioned phenol condensation product is transparent and very adhesive, and theseconditions are utilized by blowing or dusting into the bulb a small amount of pulverized dye or metal powder, preferably bronze powder, which immediately adheres to and incorporates with the phenol condensation product film so that from the exterior, the latter assumes the appearanceof a bronze-coating or shell. Thereafter, the bulb with the bronzed phenol condensation product coating is subjected to heat eA g. by being placed in a baking oven,'and the said phenol condensation product baked to the glass of the bulb, say. for about four hours or so at a temperature of about 350 F., more or less. The

phenol condensation product has by this treatment been changed to a rmly adherent and hard coating or shell upon the inside of the tube, and has the appearance of a bronze coating or actually metal foil. Of course, inasmusch as the phenol condensation product is in itself clear, it may be colored by powdered dyes or treated with other metal powders or leaf, according to the metallic appearance or color and shade desired.

When this step has been satisfactorilyv completed, the bottom of the bulb is partly filled with pieces of an asphaltic binding material such as sealing wax and thereafter a suiiicient amount of shot or the like is inserted so as to lie above the wax, the amount of such shot being added to the point of proper calibration of the instrument as a whole. The calibration, of course, includes the insertion of a graduated strip within the stem at 5 or the stem may later be etched with the desired graduations, more shotbeing'added if necessary. When the proper amount of shot are thus inserted, the bulb is heated to melt the wax gradually so that the shot or ballast will sink down generally through the wax l I and become quite evenly distributed throughout the bottom of thebulb as at lll. When the shot has finally disappeared below the upper surface of the wax, the bulb is no longer heated, but at this juncture a further small quantity of bronze powder is blown into the bulb and will bronze the surface l2 of the wax and incorporate therewith so as to give it a uniform'appearance with the bronzed phenol condensation product coating. AThe surface of the wax is preferably hollow soA as to present an upper edge I3 within said phenol condensation product coating, tapering off thereto and being quite invisible from the exterior. AThe bulb is then of course allowed to cool, which xes the position of the ballast and the resulting specific gravity4 of the instrument so that the latter will remain perfectly erect in a iluid when the bulb is submerged therein.

Although I prefer to insert the Wax in solid 5 form and melt or soften it in the bulb, it will be obvious that if desired, I may first melt the wax before introducing it into the bulb.

It may be stated that the common procedure for Calibrating the instrument may be generally fol- 10` lowed as there is no novelty in the same but merely forms a common procedure which is necessary when producing an instrument of this nature.

The form of the bulb is exceedingly efficient, being tapered down to a reinforced conical end 15 1 which can stand very violent end blows without fracture, while the rigidly adhering coating 8 of the phenol-condensation product forms a cushion and bond between the glass walls of the bulb and the interior charge of shot and wax. This makes 20 for a greatly reinforced backing within tapered end l, augmenting its strength in a mechanical manner as well as allowing the walls of the bulb to expand and contract without danger of fracture when exposed to sudden changes of tempera- 25 ture. The interior coating of phenol condensation product then acts as a slow conductor or actually an insulator between the glass and the interior shot, which latter are also protected from too rapid absorption of heat or loss thereof, 3E)

strike the lower portion of the bulb, or should 4011 the same be so violently dropped as to cause fracture, the phenol condensation product coating tends to retain the glass fragments so as to render the latter practically shatter-proof. If the lower portion of the bulb should break for any reason 45 whatever while the hydrometer is used in a fluid, and fragments of glass be lost from the bulb the coating of phenol condensation product would still remain about the ballast and would effectively prevent contact of the ballastA itself or of the 50 shot therein with the iluid. The effect would thus be as though the ballast were made of a solid phenol condensation product, which is known to be chemically inert in most fluids with which a chemist works. Hence, no contamination of such 55 fluid would result and merely the hydrometer itself would form the item of loss.

Manifestly I may use other condensation products of phenol instead of the product commonly known as bakelite, or'other substances which e0'- would serve in place thereof, while on the other hand the wax may be the common sealing wax, or any other wax on the market, even such as are erroneuosly termed gums. The form of the bulb may also be altered to suit, but the form 55 illustrated is that preferred.

Various modifications may naturally be resorted to within the scope of my invention and certain features may be used without others.

Having now fully described my invention, I 70 claim:

1. In a hydrometer or similar article having a graduated upper portion, the combination, with a lower reinforced float bulb portion attached thereto terminating in a tapered lower extrem- 75= ity which is also tapered interiorly in an unbroken manner and provided with a loaded ballast means containing a wax body set within said bulb portion, of means for greatly reinforcing said bulb against shock and in case of fracture tending to adherently and positively retain fragments of the broken glass in place while presenting an attractive and finished appearance to the eye, also presenting a substantially chemically inert surface to fluids in which the hydrometer may be inserted in case any glass fragment should become detached, comprising a closed integral reinforcing extension and uninterrupted thickening of the tapered extremity of the bulb conforming with the general outline of said tapered extremity, and a deposited coating of a phenol condensation product impregnated with a powder of metallic appearance closely and firmly adhering directly to the interior surface of the bulb from within the extremity up to a predetermined level and forming an insulating and cushioning bond between said interior surface and said ballast means, which powder in the coating conceals said ballast means within said bulb.

2. In a hydrometer or similar article having a graduated upper portion, the combination, with a lower reinforced float bulb portion attached thereto terminating in a tapered lower extremity and provided with a loaded ballast means containing a wax body set within said bulb portion, of means for greatly reinforcing said bulb against shock and in case of fracture tending to adherently and positively retain fragments of the broken glass in place while presenting an attractive and finished appearance to the eye and also presenting a substantially chemically inert surface to iiuids in which the hydrometer may be inserted in case any glass fragment should become detached, comprising a closed integral and elongated reinforcing extension and uninterrupted thickening of the tapered extremity, a corresponding shortening and uninterrupted progressive incurving of the interior space of the bulb is that the interior walls thereof converge so as to gradually increase the cross section of the bulb walls in unbroken and progressive manner downward toward a point at which they merge to form the integral lower tapered eX- tremity of said bulb, and a closely adhering interior coating of a phenol condensation product extending from a predetermined level within said bulb fully down to said point Where the interior walls merge and forming an insulating and cushioning bond between said interior walls of the bulb and the loaded ballast means within the same.

FRED V. I-IIERGESELL. 

